Can I Smoke Weed While Pregnant?

The obvious answer to "Can I smoke weed when I'm expecting a baby?" is likely to be a short, sharp "No." But how much do we actually know about the impact of cannabis on a growing fetus? In short, how much do we know about the "why"?

"It's a trade-off," said David Baranger, Ph.D., a neuroscientist and postdoctoral research associate at Washington University in St. Louis. "Cannabis carries risks, it isn't only benefits. There's a lot of marketing suggesting that cannabis is a natural, plant-based product and has no side effects and is very benign. And the research doesn't fully support that.

"There's a lack of evidence that cannabis is harmful, but that comes primarily from a lack of research being conducted, and that's because it's historically been very hard to fund cannabis studies and conduct cannabis research, because of its criminal status," Baranger continued.

A running theme is that not enough is known about smoking weed while pregnant. But it's important to remember that the lack of research certainly doesn't mean marijuana is risk-free, as Baranger said.

How many people smoke weed while pregnant?

Marijuana certainly may be tempting for many pregnant people.

"Marijuana is known to improve nausea and anxiety and lower the risk of seizures, all of which may have a beneficial effect on a mother," said Betsy Greenleaf, D.O., a triple-board-certified urogynecologist and CEO of the Pelvic Floor Store in New Jersey.

There may not be a definitive answer to the question of "How many people smoke weed while pregnant?" But a 2020 study published by the Centers for Disease Control and Prevention (CDC) analyzed data from eight states that participated in the 2017 Pregnancy Risk Assessment Monitoring System (PRAMS) marijuana supplement.

"Overall, 9.8 percent of women self-reported marijuana use before pregnancy, 4.2 percent during pregnancy and 5.5 percent after pregnancy," the report said. "The most common reasons for use during pregnancy were to relieve stress or anxiety, nausea or vomiting, and pain. Smoking was the most common mode of use."

The authors noted that the study was subject to multiple limitations, namely, that the findings are not generalizable to populations in other states.

What effect can smoking weed have on the growing fetus?

"From a purely obstetrical viewpoint, heavy use of marijuana in the first trimester will have the most detrimental effect on a pregnancy," Greenleaf said. "As with most drugs, the most concerning time of consumption is…when the fetus is forming all of its parts. For many women, they don't know they are pregnant until four to eight weeks after conception. If marijuana was going to affect a pregnancy severely, it would occur during this time period. In theory, occasional use and use later in pregnancy may not have as much of a detrimental effect, but we don't know for sure."

"Cannabis exposure may disrupt normal brain development of a fetus," added Kevin Alten, M.D., an associate professor at Marietta College in Ohio. "Manifestations of in utero exposure include impaired cognition and increased sensitivity to drugs of abuse."

Scientifically, how does this effect on development occur? It involves THC, or tetrahydrocannabinol, the compound present in marijuana that makes users high.

"It is known that THC crosses through the placenta, but there is no correlation between how much makes it to the fetus," Greenleaf said. "It is believed that fetal levels of THC are much lower than the mother, and this also depends on the route by which the mother consumes the cannabis: smoking versus edibles."

What impact can smoking weed during pregnancy have on newborns?

"Babies whose mothers used cannabis during pregnancy may be smaller at birth," Alten said.

The CDC report, too, noted that lower birthweights in exposed infants have been documented.

"Research suggests an increased risk of stillbirth," Alten added. "It is not known if this is only because of cannabis use or due to use of other substances along with cannabis such as cigarettes or alcohol."

However, Alten also said no good data exists concerning cannabis use during pregnancy. More research needs to be done on exactly how smoking weed while pregnant impacts a child at both fetal and neonatal stages, as well as how it impacts the mother.

Can smoking weed while pregnant impact a child growing up?

Baranger and a team of collaborators have been studying the mental health effects of prenatal cannabis exposure from childhood to early adolescence.

"We were following up on [a] previous study which showed that prenatal cannabis exposure was associated with poor mental health outcomes," Baranger said.

"We found…that the effects that we had previously observed persisted," Baranger continued. "The kids who had prenatal cannabis exposure continued to have elevated psychopathology."

Psychopathology, as Baranger explained, is the scientific term for a person's mental health, focused on aspects such as depression or anxiety, and aggression or psychotic-like thoughts, among others.

Baranger pointed out that this small increase in the burden of psychopathology symptoms in children who had experienced prenatal cannabis exposure could be alarming.

"Adolescence is a period when many mental health disorders first have their onset," he explained. "Many people who live with mental health disorders first experience symptoms, or even receive diagnoses, in their adolescence. So it's a period of increased risk for mental health problems, and these now-teens are entering adolescence already at elevated risk for worse mental health outcomes."

Like so many studies on this topic, there are limitations.

"The mothers are reporting on their [cannabis] use a decade ago," Baranger pointed out.

Baranger put forward another limitation: this was an observational study.

"We can't rule out the possibility that these kids would be experiencing elevated mental health symptoms anyway," he explained, adding, "Cannabis needs to be more easily studied."

What if you just found out you're pregnant?

"Because so much is unknown about the absolute effects of cannabis on pregnancy, if the mother is using marijuana recreationally, I would highly recommend stopping the use for the remainder of the pregnancy and until done breastfeeding," Greenleaf said. "[But] if one is a regular recreational user of marijuana and finds out they are pregnant, don't be hard on yourself. Stress can be as detrimental to pregnancy as other factors. Be honest with your healthcare practitioners; they are there to help, not judge."

And, as Baranger said: "If you're at the point in your pregnancy when you are thinking seriously about cannabis to treat your nausea, talk to your doctor."

Ultimately, consulting a healthcare professional is always the ideal route if you're the slightest bit concerned about anything to do with your pregnancy.